The Environmental Protection Agency (EPA or Agency) is proposing three actions pursuant to section 181(b)(2) of the Clean Air Act (CAA) related to the attainment date for 31 areas classified as ``Marginal'' nonattainment for the 2015 ozone National Ambient Air Quality Standards (NAAQS). First, the Agency is proposing to determine that six areas attained the standard by the applicable August 3, 2021, attainment date. Second, the Agency is proposing to grant a 1-year attainment date extension for the Uinta Basin, Utah, nonattainment area.